MATERIALS PERFORMANCE OF FERRITIC STEEL IN COMBUSTION GASES FOR HEAT EXCHANGER APPLICATIONS IN SOLID OXIDE FUEL CELL SYSTEMS

摘要

Ferritic steels have been recognized as candidates for their applications in heat exchangers used in Solid Oxide Fuel Cells' balance of plant. Combustion gases flowing through those heat exchangers can be very corrosive. Therefore, the National Energy Technology Laboratory determined materials performance of commercial S43000 stainless steel exposed to a simulated combustion gas at 800 °C. The exposure experiments were conducted on flat samples in the simulated combustion gas: 19vol% O_2+6vol% H2_O + 4vol% CO_2 +71vol% N_2 under isothermal conditions. After the experiment, the surface of a corroded sample was characterized by X-ray diffraction (XRD) to identify possible phases present in the scale, scanning electron microscopy (SEM) to determine microstructure of the oxide scales, and energy dispersive X-ray (EDX) or wavelength dispersive energy X-ray (WDX) spectroscopy to determine chemical composition in the scale and the metal substrate.